Andras, HA7ILM's blog

Debian package for 32-bit GitHub Atom text editor

I've recently had difficulty installing GitHub Atom on my PC as only an amd64 package was available on the official site.
Here I'll provide an i386 build:


It looks something like this:

I've tested the package on Linux MINT 16 (which is based on Ubuntu, so that should also work).

Online LibreOffice Equation to Octave/MATLAB converter for Matrix Expressions

It was created to quickly enter some of my LibreOffice Equations to GNU Octave. Please note that It is very limited, as it was created for a specific purpose.

Calculating CPU usage with python on Linux

This small script prints overall CPU usage in a Linux system. You can use the get_cpu() function to get the CPU usage between 0.0 and 1.0 (all CPU cores were taken into consideration, so the maximal value is also 1.0 on a multi-core system).

Returning structs in emscripten

Based on the discussion over here, I've created a simple code sample.

C code:

typedef struct shift_addition_data_s
	float sindelta;
	float cosdelta;
	float rate;
} shift_addition_data_t;

shift_addition_data_t shift_addition_init(float rate)
	shift_addition_data_t out;
	return out;

How to call it from JavaScript:

LUT based frequency translation in libcsdr

I've just written a shift_table_cc function for libcsdr.

This function uses a LUT to calculate the sine and cosine waves required for shifting the spectrum.
The first quadrant of the sin(x) function is stored in the LUT. The resolution (sine table size) is given as a parameter.

I've been testing different sine table sizes. Below some results are presented.

For value 30:

For value 1000:

OpenCL on Linux Mint 17 and NVIDIA Quadro 1000M

You will need something like this (note that I have xorg-edgers and you may have to replace 346 with the actual version number).

sudo apt-get install nvidia-libopencl1-346 nvidia-opencl-icd-346 opencl-headers ocl-icd-opencl-dev ocl-icd-libopencl1 you can compile a test program:

git clone
cd tools
./cl-demo 1000000 10

Script for easy scanning with a Samsung SCX-4521F

For Linux Mint 16. Requires SULDR, scanimage, imagemagick.


Some notes on ShinySDR

ShinySDR is a bit similar to my OpenWebRX project.

I could not find any good screenshots on the internet about ShinySDR, so here is one:

On the picture, I'm just demodulating NFM, and it works well.

OpenWebRX performance tests

OpenWebRX serving 10 clients simultaneously (and also running the browser windows on the same machine), without audio underruns.

  • Server CPU: Intel Core i7
  • samp_rate: 1024000

I had to increase the number of clients above 15 to notice the first underrun (although it was still usable).

[fun] The best antenna ever


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